Generally, a combination scale is an apparatus which repeatedly performs a procedure of combining into various combinations the weight signals generated by multiple weighing devices which each weigh articles, selecting from among these combinations the combination which has a total weight closest to a predetermined weight, discharging the articles from the weighing devices comprising the selected combination, and providing a new supply of articles to the emptied weighing devices. In addition, a packing machine being operated in conjunction with a combination scale is an apparatus which is used to pack the articles discharged from the combination scale into a bag or other such container. Examples of technology in this area are described for instance in U.S. Pat. Nos. 4,391,079 (packing machine control) and 4,553,616 (combination scale), and in U.S. Pat. No. 4,780,830 filed Oct. 7, 1986 (operation and display unit interfaced to both packing machine and combination scale) all of which are incorporated herein by reference.
Of course, if the type of article being supplied to the weighing devices is changed, it becomes necessary to change the operation conditions of each of the devices which constitute the combination scale, and it also becomes necessary to change the operation conditions of each of the devices which constitute the packing machine. Examples of operation conditions for a combination scale are target weight, allowable deviation from target weight, and vibration feeder amplitude and duration. Examples of operation conditions for a packing machine are bag length and rate of delivery or operation speed. The just-stated operation conditions correspond to sets of numerous values and settings (also referred to as "operation conditions") for the many devices in the combination scale and packing machine.
Changing the operation conditions requires a considerable amount of time and specialized knowledge, thus making it unduly difficult for a typical packing company to make the changes. For these reasons, it is standard practice to store for each separate type of article the operation conditions for each of the devices which constitute the combination scale in a combination scale memory which is provided in the combination scale and also store for each separate type of article the operation conditions for each of the devices which constitute the packing machine in a packing machine memory which is provided in the packing machine, and then to retrieve the new operation conditions from these two memories and supply them to the various corresponding devices each time the type of article is changed.
However, although the operation conditions sent to the combination scale and to the packing machine must both correspond to the same type of article, because the conditions are retrieved separately from the combination scale memory and from the packing machine memory, there has existed the problem of the possibility of the two not corresponding and consequent incorrect operations of the combination scale and the packing machine when used together.